Goniatids, informally goniatites, are ammonoid cephalopods that form the order Goniatitida, derived from the more primitive Agoniatitida during the Middle Devonian some 390 million years ago (around Eifelian stage).

All goniatites possessed an external shell, which is divided internally into chambers filled with gas giving it buoyancy during the life of the animal.

The general morphology and habit of goniatites was probably similar to that of their later relatives the ammonites, being free swimming and possessing a head with two well developed eyes and arms (or tentacles).

Goniatitid shells vary in form from thinly discoidal to broadly globular and may be smooth or distinctly ornamented.

Due to lack of strong evidence for any particular life mode (e.g., benthic, nektonic, and planktonic), it remains unclear what resources goniatites were capitalizing on in these offshore environments.

However, goniatites clearly lacked the calcified jaw apparatuses developed in later ammonites; this has been cited as evidence against their having a durophagous (shell-crushing) diet.